Which numbers are necessary to solve this problem?
brian goes to the gym 3 times a week. he exercises for 45 minutes each visit. fifteen of those minutes are spent on weights and the rest are spent on the treadmill.
how much time does brian spend on the treadmill in 4 weeks?
a.
3 times a week, 45 minutes, 15 minutes, 4 weeks
b.
3 times a week, 15 minutes, 4 weeks
c.
3 times a week, 45 minutes, 4 weeks
d.
3 times a week, 15 minutes

A

Step-by-step explanation:

A: 3 times a week, 45 minutes, 15 minutes, 4 weeks

In the beginning of the word problem it says Brian goes to the gym 3 times a week. We need to know that because you have to use that number later for multiplication.

The 45 minutes are important because he spends 45 minutes at the gym each visit.

The 15 minutes are important because you have to subtract that from 45 because 15 of the 45 minutes are spent on weights, the rest of the time is spent on the treadmill, and we need to know how long Brian is on the treadmill in 4 weeks.

So the equation should be: [(45-15)* 3]*4

Solution step-by-step:

45-15= 30 minutes for treadmill

30*3=90 minutes per week

90*4= 360 minutes in 4 weeks

Convert into hours:

360 minutes/60 minutes= 6 hours

Hope this helps!!! :D

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240